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My Eco Friendly Cross Country Transport!
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So its 3am and I am awake and therefore check my Leaf is charging and the cost on Economy 7 (as every "sane" person would of course), which is 55p an hour at ~6.5kW, 92% and about 1.5 hours to go - all pretty much as expected. My charging protocol is plug in every night regardless of whether the car needs 80% or 5%. But mostly I use around 15-20% of capacity a day, so don't really need to charge every night.

Then I start thinking about charging protocol and cost. I know that on a rapid charger the the rate is tapered so that as you exceed 60% and head to higher levels the charging rate drops and it takes longer to "fill" those last percentage points, but the rate is less. Does that apply to to the 7kW charger at home - the figure above suggest not? It is still using 6kw at 92% heading to 100% but is it "filling" at the same rate as when charging at a lower percentage (i.e. Does it take the same time and use the same charging rate/kW to go from 50% to 60% as 90% to 100%) or is it costing me more topping-up to 100% each night?
 

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There are some losses involved with charging, so charging every night in your case might waste a couple of pence here and there.
With your use case charging every couple of days or every 3 days is probably easier.

If you look in the handbook it has recommendations for charging, it always used to say don't charge if the battery is already at 85% unless you really need that extra range.
 

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I read on this forum that the battery health degrades faster if SOC is high for a prolonged period.

Therefore as a new owner (3 weeks) I have so far adopted the strategy of not charging unless car is below 50-60 percent, unless I have a big journey ahead. Most days the car is only in use for school runs and other short journeys.
 

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Here's mine charging from about 50% overnight (other days I graze-charge from solar PV but needed the ranger the next day); I have no idea how it would behave from less than 50% or so, but the tapering is for about an hour plus the three little "blips" after.

upload_2018-6-11_9-49-26.png
 

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As noted above - with a Leaf 40, which has enough range for most days to be covered with much less than a full charge, I'd be inclined to only plug in once charge drops below about 50-60% unless you think you might need to drive a lot the next day. It'll be better for your battery not to spend as long at 100% - the life of the battery is greatly extended by mostly keeping to the middle of the charge range (don't leave it sitting at or near either 100% or 0%). Some of that will be taken care of by Nissan deliberately not over-charging the cells in the first place (a 100% charge will only in reality be using something like 90% of the theoretical maximum the cells could be charged to if battery life wasn't a consideration), but it can't hurt much to be a little cautious if it doesn't cause you any inconvenience.

Having said all that, the car is there to do a job - if you do occasionally find yourself having to make unexpected long journeys, then err on the side of usefulness by charging nightly - it might slightly increase the rate of battery degradation but not to any particularly great degree.
 

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In particular what you really don't want to do is leave the car sitting at 100% while you go away for your 4 week extended summer holiday... Sitting at "full charge", especially in high temperatures, for an extended period is just about the worst thing (other than leaving it at 0%) that you can do to the battery.
 

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I tend to charge when I know I’ll need more than the range in the car.

At the moment I haven’t used the car since Thursday due to having an operation. It is sitting at 88%.

Tomorrow I have to drive to Birmingham. I will top up tonight so I can do the trip without rapid charging, but when I reach my destination I will rapid charge at the hotel I’m staying at.
 

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My Eco Friendly Cross Country Transport!
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Discussion Starter #8
Thank you to everyone for their thoughts and information.

I think for us we will stick with every night charging as we drive everyday and while not worried about range normally, we (i.e my wife) would feel uncomfortable should an emergency arise and we had to drive a significant distance with children having flown the nest (Staggered out of? Been kicked out of? Not really left? Still have a bedroom!)

I am also using the "spare" capacity in this lovely weather (UK) to keep the car cool by remote cooling "just in case".

But will also take the advice of not leaving at 100% when on holiday.
 

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If you set the charge timer to finish just before you typically use the car in the morning you won't do it much harm even charging to full every day.

My personal routine (with a Leaf 24) is to set the timer to charge to 80% every night except Monday (when I might go to the cinema in the evening, perhaps) when I have it charge to 100%.
 

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Unfortunately, we can't set a 80% charge maximum with the 40kWh Leaf. It's 100% or turn it off yourself. You can try and work it out with the timer and set it stop charging at a certain time.
Really it shouldn't be that hard for Nissan to allow you to set a required charge level, but I wouldn't hold out much hope of them actually implementing anything... A little disappointing.
 

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My daily commute is 44 miles all-in. Initially I charged every night, but I think that was just range anxiety, so now I'll do it every other night. That said we do have the fall-back of the wife's ICE if we need to hit a heavy journey at short notice.
 
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